Fuel Surcharge Calculator: The Formula, a Worked Example and Rate Tables

There’s no official fuel surcharge. The U.S. Energy Information Administration publishes the diesel price nearly everyone uses, and its own FAQ says the agency “does not calculate, assess, or regulate diesel fuel surcharges.” Surcharges, in EIA’s words, “are negotiated privately by shippers and by transportation companies.”

So the formula is whatever the contract or the rate confirmation says it is. The calculator below uses the standard per-mile method. After it comes the math, where each input comes from, and the percent-of-linehaul method LTL carriers use.

The fuel surcharge formula

The per-mile method has three inputs and one line of math:

Surcharge per mile = (current diesel price minus base price) divided by miles per gallon

Multiply the result by the miles on the load. Here’s the example from the top of the page, one step at a time.

1. Diesel is $6.382 and the agreed base is $1.25. The difference is $5.132 a gallon.
2. The agreed fuel economy is 6.5 mpg. $5.132 divided by 6.5 is $0.7895, which rounds to $0.79 a mile.
3. The load is 500 miles. $0.79 times 500 is $395.00.

Both OOIDA and FreightWaves describe the method the same way. OOIDA also gives the shortcut drivers use: at 6 mpg, the surcharge goes up one penny a mile for every 6 cents diesel rises above the base.

Where each number comes from

The diesel price

Most schedules use EIA’s weekly U.S. on-highway diesel price. EIA posts it every Tuesday on its Gasoline and Diesel Fuel Update, dated for Monday. The U.S. average for September 28, 2026 was $6.382 a gallon. That was down from $6.529 the week before and $2.628 higher than the same week a year earlier.

EIA also publishes regional prices, and the gap between regions is wide. Your agreement should name which one it uses.

The base price

The base is the fuel cost already built into the linehaul rate. The surcharge only pays for diesel above it. There’s no standard base. FreightWaves reports that U.S. trucking contracts commonly set it between $1.25 and $1.50 a gallon, while OOIDA’s worked example uses $2.50, taken from the carrier’s own cost figures.

A higher base means a smaller surcharge, and it should come with a higher linehaul. At $6.382 diesel and 6.5 mpg, a $1.25 base gives $0.79 a mile, a $1.50 base gives $0.75, and a $2.50 base gives $0.60.

The miles per gallon

This is an agreed number, and the truck’s real mileage on the trip doesn’t change it. OOIDA uses about 6 mpg for a loaded tractor-trailer. FreightWaves puts typical contract assumptions at 6.0 to 7.5 mpg. For a national benchmark, the Federal Highway Administration’s Highway Statistics puts combination trucks at an average of 7.1 mpg in 2024. A lower mpg in the formula means a higher surcharge.

The other method: a percent of linehaul

LTL carriers usually skip the per-mile math. They publish a table that ties each band of the EIA diesel price to a percentage, and that percentage is applied to the linehaul charge.

Old Dominion’s published schedule moves in 5-cent bands. Diesel at $3.00 means a 24.07 percent surcharge, $4.00 means 30.82 percent and $5.00 means 40.82 percent. Above $5.10, the tariff adds half a point for every 5 cents. At $6.382 that comes to 54.32 percent, which is the LTL surcharge Old Dominion posted for October 7 through 13, 2026.

The table is the whole story with this method. The U.S. Department of Energy’s 2026 freight surcharge schedule uses the same $6.382 diesel price and lands on 42.0 percent for LTL and $0.83 a mile for truckload. Same fuel price, different table, different charge. You can’t check a percent surcharge without the carrier’s own schedule in front of you.

Two details to read for: when the schedule changes, and what the percentage applies to. ABF Freight, for one, adjusts each Wednesday from the prior Monday’s price and applies the surcharge to linehaul charges after discounts, with special service charges left out. For more on how LTL pricing differs, see LTL vs. FTL.

How a fuel surcharge shows up on a brokered load

A broker has two rates on every load, and fuel can be handled differently on each one.

Spot quotes are usually given all-in, with fuel already inside the number. Contract freight more often splits the price into linehaul plus a fuel surcharge tied to a schedule. If your customer pays a surcharge that floats every week and your carrier is on a flat all-in rate, your margin moves with diesel. Know which side of that you’re on before the price jumps.

Whichever way you price it, put the terms in writing on the rate confirmation:

• whether the rate is all-in or linehaul plus fuel
• the base price and the miles per gallon
• which EIA price applies, national or regional, and for which week
• the miles the surcharge is paid on, and where that mileage comes from

Miles cause more arguments than the formula does. A surcharge is paid on billed miles. Deadhead miles to the pickup aren’t billed miles unless the agreement says they are. Our rate confirmation checklist lists the rest of what belongs on the page, and the accessorial charges guide covers the other add-ons, such as detention and lumper fees.

What fuel costs a carrier

The surcharge exists because fuel is one of a carrier’s biggest costs and the one it controls least. The American Transportation Research Institute’s 2026 cost study put the average cost of running a truck at $2.336 a mile in 2025, and at $1.854 a mile with fuel taken out. The gap, about 48 cents a mile, is fuel.

Those are 2025 averages, and diesel has climbed since. At 6.5 mpg, every extra dollar on a gallon of diesel adds about 15 cents to the cost of every mile. A surcharge that tracks the weekly price is how a carrier keeps hauling a contract lane when that happens.

Five fuel surcharge mistakes

1. Quoting on last month’s diesel price. The number changes every Tuesday, and in September 2026 it moved 24 cents in one week.
2. Comparing two surcharges without comparing the base. A $0.60 surcharge on a $2.50 base and a $0.79 surcharge on a $1.25 base cover the same diesel price. The rest of the fuel cost is sitting in the linehaul.
3. Applying a percent surcharge to the whole invoice. Carrier schedules apply it to linehaul, so check before you put it on accessorials too.
4. Paying the carrier on one mileage and billing the customer on another.
5. Leaving the schedule off the rate confirmation and sorting it out at invoice time.

Final thoughts

The math takes ten seconds. The arguments come from the three numbers that go into it, so agree on the base, the mpg and the price index before the truck is loaded, and write them down. Then check EIA on Tuesday. If you’re setting up the rest of the back office, our guide to choosing a freight broker TMS covers what the software should handle.